The present invention relates to a device and a method for sampling of milk from an animal the milk of which is to be tested, wherein the device comprises a collecting member arranged to receive milk samples from a milk line, which is arranged to transport milk from one animal at a time, and a passage arranged to allow a milk flow from a milk line to the collecting member.
Sampling of milk is performed in order to analyse the quality of the milk. Thereby, the content of particular substances and the existent of bacterium in the milk of individual cows may be analysed. Usually, tubes having a relative small inner diameter are used for delivering milk samples from a milk line to a milk analysing device. Inevitably, milk residues from previous samplings are stored as a thin film along the inner walls of such tubes. Thereby, the amount of milk forming this film is not negligible in relation to the whole amount of milk in a sample. Consequently, the risk is obvious that milk samples conveyed in such tubes comprise a relatively high percentage of milk from previously milked cows. Thereby, the result of the analysis of a milk sample from a specific cow may be influenced of milk from previously milked cows.
Somatic cell count (SCC) defines the number of white cells per millilitre of milk. SCC scores are used as an international standard in determining the quality and the price of the milk. In order to determine the number of somatic cells in a milk sample, it is extremely important that the milk sample does not contain milk residuals from the previously milked cow, so-called carry over. In such a case, the measurement result could be completely incorrect. In an automatic milk arrangement, it is a desired to provide an automatic analysis of the number of somatic cell in the milk from individual cows. In this case, it is a problem to provide a quick and effective washing of the passage, through which milk samples are delivered to a milk analysing device.
WO 92/15196 shows an apparatus for sampling of milk from a milk line. The apparatus comprises a by-pass line comprising a pump, a timer, a sampling valve, and a test actuator. A milk flow is obtained in the by-pass line during a test period when the timer is set in a position, which initiates activation of the pump. Thus, a milk flow through the by-pass is here obtained during the sampling time period. There is a big risk that milk residues from a previous milked cow in the by-pass line are mixed with the milk sample of the cow, which is to be tested. In an embodiment of this invention, the milk is guided into the by-pass line via an inlet opening in a collector. After the milk has passed through the by-pass line, it is guided back to the milk line, via an outlet opening, to the collector. The outlet opening in the collector is positioned at a small distance downstream of the inlet opening. Especially at a low milk flow in the milk line, it is an obvious risk that milk from different cows is mixed in the collector and milk from previously milked cows is guided back into the inlet opening of the by-pass line.
DE 23 54 820 shows a milk line having an extension between a first container and a second container. A conduit has an extension between these containers in parallel with the ordinary milk line. A sampling device is arranged to allow sampling of the milk in the conduit. The sampling device, which has a relatively complex construction, is arranged to discharge milking samples from the conduit, via a branch conduit, to a sample container.